Boo.Lang.Compiler.Steps.ProcessMethodBodies.BuildNullableCoalescingConditional C# (CSharp) Метод

        private Expression BuildNullableCoalescingConditional(Expression exp)
        {
            if (IsNull(exp)) return null;

            IEnumerator<Expression> enumerator = FindNullableExpressions(exp).GetEnumerator();
            Expression root = null;
            BinaryExpression and = null;
            Expression lookahead = null;

            while (enumerator.MoveNext())
            {
                Expression cur = enumerator.Current;
                lookahead = enumerator.MoveNext() ? enumerator.Current : null;
                if (null != and)
                {
                    and.Right = new BinaryExpression(
                                        BinaryOperatorType.BitwiseAnd,
                                        and.Right,
                                        new BinaryExpression(
                                            BinaryOperatorType.BitwiseAnd,
                                            CreateNullableHasValueOrTrueExpression(cur),
                                            CreateNullableHasValueOrTrueExpression(lookahead)
                                        )
                                    );
                }
                else
                {
                    if (null == lookahead)
                        return CreateNullableHasValueOrTrueExpression(cur);
                    root = and = new BinaryExpression(
                                    BinaryOperatorType.BitwiseAnd,
                                    CreateNullableHasValueOrTrueExpression(cur),
                                    CreateNullableHasValueOrTrueExpression(lookahead));
                }
            }

            return root;
        }